Antioxidant Effects and Suppression of Nitric Oxide Production in LPS-stimulated Macrophages by Fractions of Vaccinium leschenaultii Wight

Abstract

ABSTRACTSolvent fractions from leaf and bark extracts of Vaccinium leschenaultii were screened for their antioxidant, cell viability, and nitric oxide (NO) inhibitory potential. Antioxidant activities were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH), total antioxidant activity (TAC) and Oxygen Radical Antioxidant Capacity (ORAC) assays. Sulforhodamine B assay was used to estimate the cell viability of RAW 264.7 cells. Griess reagent was used to measure the NO production, which was induced by lipopolysaccharide (LPS) on RAW 264.7 cells. Higher antioxidant activity was observed in the fraction of V. leschenaultii bark ethyl acetate: methanol extract (VBEM, 60/40, v/v) in DPPH (IC50 = 20.80 µg mL−1), TAC (14.90 mmol uric acid equivalents/mg extract) and ORAC (454.58 µmol trolox equivalents/mg extract) assays compared to the leaf extracts. Similarly, VBEM (60/40) fraction also showed 83.87% of RAW 264.7 cell viability. V. leschenaultii leaf ethyl acetate: methanol extract (VLCE, 70/30, v/v) inhibited the NO production (90.06%, IC50 = 1.61 µg mL−1) and showed dose-dependent activity without inhibiting the macrophages. V. leschenaultii leaf and bark fractions from the methanol extract inhibited the free radicals including NO by modulating the macrophage-mediated inflammatory functions in the in vitro system.